Markers denoting the location of landmarks and search results in mobile apps are used extensively in many applications. The presence of large volumes of markers clutters the information space, making it hard for users to visually differentiate between highly important or recommended locations, or to browse the depicted locations in order to identify suitable choices. In this paper, we present the results of a participatory design process to improve the utility of marker icons in a tourist application. We explore three alternative designs derived from this process by implementing and testing a mobile application that recommends venues based on their popularity (check-in count) in a well-known social network (FourSquare). Our lab experiments highlight aesthetic, utility and performance issues in marker design that affect the usability of mobile map applications.

We present two touchscreen smartphone keyboard interface designs which dynamically alter key sizes as the user types and highlight likely key targets, based on word completion predictions. Although we find a speed reduction and no accuracy advantage with these methods over standard QWERTY, the text entry experience on mobile devices with these designs is significantly better for users.

One popular and wide use of augmented-reality based application, is the projection of points of interests on top of the phones’ camera view. In this paper we discuss the implementation of an AR application that acts as a magic lens over printed maps, overlaying POIs and routes. This method expands the information space available to members of groups during navigation, partially mitigating the issue of several group members trying to share a small screen device. We examine two aspects critical to the use of augmented paper maps: (a) Appropriate visualization of POIs to facilitate selection and (b) augmentation of paper maps with route instructions for use in group situations. In this paper, we evaluate POI visualization in a lab setting and aug- mented paper map navigation with groups of real tourists in a preliminary field trial. Our work complements existing literature introducing self-reporting questionnaires to measure affective state and user experience during navigation.

How does a massively popular application like Instagram work? What goes on behind the scenes? What knowledge must a team of developers have to develop a service like Instagram? Together with colleague Vassilios Stefanis, I gave a presentation in the context of the 1st Summer School in ICT at the University of Patras (CEID), directed to prospective students (high-school age).